A vehicle or locomotive “consist” or system is a group of two or more vehicles (e.g., locomotives) that are mechanically coupled or linked together to travel along a route. Trains may have one or more locomotive consists. The vehicles can be interconnected electrically by multiple unit (“MU”) trainlines or MU cables so that an operator in one vehicle can remotely control operation of the other vehicles. For example, freight trains are often hauled by multiple locomotive ensembles (“consists”) placed together at the front or rear of the train or dispersed among the freight cars. A single crew at the front of the train coordinates all of the locomotive throttles and brake commands via a connection called the multiple unit line (“MU-line”) that runs among the locomotives. Another example is, if the front, or lead, locomotive is in dynamic braking operation at a specified brake level (controlled by an operator request), then all of the locomotives in the consist are also operating in dynamic braking operation at the same specified level. As such, it should be appreciated that there may be multiple consists in a train and that these consists may be set up such that all of the locomotives in each consist act in unison.
The currently known MU cables include a 27-pin cable that electrically (e.g., conductively) couples vehicles together to allow a single lead vehicle to command throttle settings and dynamic brake settings to multiple trailing vehicles in the same vehicle system. This system has several inherent advantages in that it is robust and simple, but also has several inherent drawbacks. The MU cable is a conductive pathway extending along the length of the vehicle system. The MU cable may not provide vehicle-to-vehicle isolation and, as a result, an electrical fault (e.g., a ground fault or wiring error) within one vehicle is experienced by all other vehicles connected to the MU cable. For example, if a first vehicle experiences a ground fault, then all other vehicles connected to the same MU cable may experience the same ground fault, even if only the first vehicle is the source of the ground fault.
Additionally, there may not be any ability to identify the source of signals or faults along the MU cable. If a first vehicle experiences a ground fault, then all other vehicles experience the same ground fault and, as a result, the location of the ground fault may not be able to be easily determined. The feedback that can be provided (via signals communicated along the MU cable) from the remote vehicles may be limited in that only a single line of the cable may be available for this feedback.